In a vehicle comprising an internal combustion engine and a fuel tank supplying the engine, it is known practice to provide a breather circuit that removes fuel vapors that may emanate from the fuel tank.
Such a fuel vapor breather circuit conventionally comprises a vapor purge line at the fuel tank connecting the fuel tank to the intake side of the engine.
The fuel vapor breather circuit also comprises means for collecting fuel vapors in the fuel tank and, in particular, a fuel vapor filter, commonly referred to as a “canister”, which is conventionally an active-carbon filter and which is interposed between the fuel tank and the vapor purge line. It therefore allows fuel vapors emanating from the tank to be collected, particularly when the engine is not running.
The filter is also connected to an air intake so that when the engine is running, a depression in the feed line causes air to circulate through the filter and purge the fuel vapors it contains, removing them toward the engine.
However, in certain vehicles such as hybrid motor vehicles equipped with a combustion engine and an electric motor, the combustion engine running time may be short and not long enough to purge the gasoline vapors stored in the filter. In order to prevent the fuel vapors from escaping from the fuel tank and thus filling the filter, it is known practice to position, on a line connecting the tank to the filter, a valve referred to as the tank isolation valve. This line can be opened or closed selectively in order to allow or prevent the circulation of fluid in the line, and notably to prevent vapors from leaving the tank.
The fuel tank is therefore dimensioned to withstand a higher pressure than in vehicles that do not have such an isolation valve. The pressure in the fuel tank is measured by a dedicated sensor positioned in the tank.
Now, because the components such as the fuel vapor filter, the isolation valve, and the in-tank pressure sensor have the role of limiting the emission of fuel vapors to the environment, and therefore the pollution emitted by the vehicle, these components are subject to specific legal requirements, and notably to a permanent check that they are operating correctly.
Certain checks on the in-tank pressure sensor already exist, namely an electrical diagnosis and a verification that the pressure value measured by the sensor does not lie outside of a plausible range of values. Nevertheless, there is not at this stage any verification as to the consistency of the sensor measurement, which makes it possible to determine an anomaly in this measurement if this measurement does not extend outside of a plausible range. For example, anomalies such as a sensor drift error or a blocking of the sensor value cannot be detected.